Example on how to meta query ACF repeater fields

functions.php

<?php

add_shortcode( 'user_company_link', 'yanco_user_company_link' );
function yanco_user_company_link() {

    if( ! is_user_logged_in() ) {
        return;
    }

    $html = '';
    $current_user = wp_get_current_user();
    $current_user_id = $current_user->ID;

    // Check if the user is attached to any companies
    $query_args = array(
        'post_type' => 'virksomhed',
        'post_status' => 'publish',
        'suppress_filters' => false,
        'meta_query' => array(
            'relation' => 'OR',
            array (
                'key' => 'acf_virksomhed_admins_$_user',
                'value' => $current_user_id,
            ),
            array(
                'key' => 'acf_virksomhed_users_$_user',
                'value' => $current_user_id,
            )
        ),
    );

    $query = new WP_Query( $query_args );

    if( count( $query->posts ) ) {

    }
}

add_filter('posts_where', 'yanco_posts_where');
function yanco_posts_where( $where ) {
    $where = str_replace( "meta_key = 'acf_virksomhed_admins_$", "meta_key LIKE 'acf_virksomhed_admins_%", $where );
    $where = str_replace( "meta_key = 'acf_virksomhed_users_$", "meta_key LIKE 'acf_virksomhed_users_%", $where );
	return $where;
}

@yanknudtskov: Wow, so simple and elegant, near-self explanatory! Thank you very much, this was very useful for me. Before using this query I had to iterate over all the posts, then over the repeater field of each post, which was very slow and performance intensive.
With a query there is basically no overhead.

@yanknudtskov Hi, is this still working on your end?

@heymicoo yup still works here, we're using it in several production sites currently and seems to be working as inteded :-)